• Gary Willoughby (5/10) Jul 25 2013 I've just read the article over at Dr Dobbs by Walter
• H. S. Teoh (16/29) Jul 25 2013 I can personally testify to the truth of this statement. All too often,
• Dmitry Olshansky (9/18) Jul 26 2013 I've found

"Gary Willoughby" <dev nomad.so> writes:

I've just read the article over at Dr Dobbs by Walter

http://www.drdobbs.com/cpp/increasing-compiler-speed-by-over-75/240158941

and this line caught my eye:

 Even if you know your code well, you're likely wrong about where
 the performance bottlenecks are. Use a profiler. If you haven't
 used one on your codebase in a while, it's highly likely there's
 a bottleneck in there that's fixable with just a few lines of 
 code.

What profilers do you use with D especially for Linux and Mac? 
I've been compiling with -profile and trying to grok the output.

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Thu, Jul 25, 2013 at 08:15:42PM +0200, Gary Willoughby wrote:
 I've just read the article over at Dr Dobbs by Walter
 
 http://www.drdobbs.com/cpp/increasing-compiler-speed-by-over-75/240158941
 
 and this line caught my eye:
 
Even if you know your code well, you're likely wrong about where
the performance bottlenecks are. Use a profiler. If you haven't
used one on your codebase in a while, it's highly likely there's
a bottleneck in there that's fixable with just a few lines of
code.


I can personally testify to the truth of this statement. All too often,
too much time is spent "optimizing" parts of code that are actually
irrelevant to the performance of the program, because the bottleneck
lies elsewhere, often in an unexpected place. (Not to mention that such
premature optimization makes your code harder to write, harder to read,
harder to maintain, and therefore more prone to bugs.)

I remember at least one instance in which a profiler immediately
revealed an fprintf (this was C/C++ code, back in the day) where it
shouldn't be, the removal of which instantly improved performance by at
least 30%, probably more.


 What profilers do you use with D especially for Linux and Mac? I've
 been compiling with -profile and trying to grok the output.

I use gdc with gprof, usually. I've only tried dmd -profile a few times.


T

-- 
I think Debian's doing something wrong, `apt-get install pesticide',
doesn't seem to remove the bugs on my system! -- Mike Dresser

Dmitry Olshansky <dmitry.olsh gmail.com> writes:

25-Jul-2013 22:15, Gary Willoughby пишет:
 I've just read the article over at Dr Dobbs by Walter

 http://www.drdobbs.com/cpp/increasing-compiler-speed-by-over-75/240158941

 and this line caught my eye:

 Even if you know your code well, you're likely wrong about where
 the performance bottlenecks are. Use a profiler. If you haven't
 used one on your codebase in a while, it's highly likely there's
 a bottleneck in there that's fixable with just a few lines of code.

 What profilers do you use with D especially for Linux and Mac? I've been
 compiling with -profile and trying to grok the output.

I've found
valgrind --tool=callgrind
+ kcachegrind
to be quite awesome.

Other options are the usual profilers of your OS/CPU vendor:
perf, AMD CodeAnalyst, Intel VTune

-- 
Dmitry Olshansky